This invention relates to circuits, such as a circuit for trimming input offset voltage.
The input offset voltage of an operational amplifier (op amp) can be defined as the potential that must be applied between the input terminals of the op amp to provide a zero output. Thus, an op amp having a predetermined input offset voltage causes a non-zero output to occur when the voltage applied between the input terminals of the op amp are equal. Further, the input offset voltage is typically due to base-emitter voltage mismatches between input transistors of the op amp. In addition, the input offset voltage error is typically gained up through the later stages of the op amp thereby creating an even greater offset voltage error.
One attempt to minimize the input offset voltage of an op amp is to design a precision op amp having cross coupled transistors and perfectly matched circuit blocks. However, precision op amps consume a large amount of die area and are expensive to build.
Hence, there exists a need for an improved circuit to trim the input offset voltage of an op amp.